The present invention is directed at an additive for a functional fluid. More specifically, the present invention is directed at an ashless anti-wear additive for lube oil.
Several factors are combining to increase the demands on the wear protection capability of passenger car engine oils. In the formulation of lube oils, an anti-wear additive frequently is added to decrease the wear associated with operation. In lube oils for internal combustion engines, the anti-wear additive often comprises a phosphorus compound, such as zinc dialkyldithiophosphate. While this additive has proven effective in reducing engine wear, the phosphorus present has been determined to be a catalyst poison, when minor amounts of the lube oil are combusted in the internal combustion engine.
In addition, the severe operating conditions of high speed engines and the use of fast burn engines with higher combustion temperatures increase the oil sump temperature. Moreover, engine manufacturers are recommending lower viscosity oil, such as 5W30 for faster cold starting and improved fuel economy.
U.S. Pat. No. 3,374,173 discloses 2,4,6 tri-amino substituted pyrimidines are effective in imparting high temperature stability to lubricants. In a preferred embodiment the tri-amino substituted pyrimidine is prepared from a 2,4,6 trichloropyrimidine.
Japanese Patent Publication No. 58,103,594 discloses the addition of a substituted benzothiazole as an anti-wear additive for a lubricating oil used in freon compressors.
In "Boundary Lubricating Studies Structure-Activity Correlations in Alkylpyridines", Journal of the Institute of Petroleum, Volume 59, Number 565 (January, 1973), A. H. Miller discloses that pyridine, benzopyridine and certain alkylpyridines are effective as anti-wear agents in lube oils.
U.S. Pat. No. 4,113,725 discloses compounds of the general formula: ##STR1## in which X is a heterocyclic radical derived from pyridine, pyridazine, pyrimidine, pyrazine or triazine; and A, B and C are each hydrogen, alkyl, aralkyl, alkenyl, aryl, alkaryl, hydroxyalkyl, hydroxyaryl, carboxy, alkylcarboxy, hydroxy, phosphono, phosphato, sulfonato, mercapto or a nitrogen-containing substituent having from about 1 to about 500 atoms, preferably from about 1 to 100 carbon atoms, provided that at least one of A, B, or C is one of the nitrogen-containing substituents. The nitrogen-containing substituents include alkyl-amino, arylamino, succinimide amino, lactam amino and the like.
Accordingly, it would be desirable to provide a phosphorus-free anti-wear additive for a functional fluid, such as a lube oil.
It also is advantageous to provide anti-wear additive for a lube oil which is soluble in the lube oil and which is effective at relatively low concentrations. It also would be desirable to provide an ashless anti-wear additive to minimize depositions on catalytic converters.
The present invention is directed at an additive for a functional fluid, such as a lube oil comprising:
A. a basestock; and
B. an anti-wear compound selected from the group consisting of substituted pyridine, pyrimidine, pyrazine, pyridazine, fused ring derivatives thereof and mixtures thereof.